A liquid crystal display has a liquid crystal cell and a polarizing plate. The polarizing plate normally has a protective film and a polarizer and is obtained by dyeing a polarizer made of a polyvinyl alcohol film with iodine, stretching the polarizer thus dyed, and then laminating the polarizer with a protective layer on the sides thereof. A transmission type liquid crystal display comprises a polarizing plate attached to the both sides of a liquid crystal cell and optionally one or more sheets of optically-compensatory film provided therein. A reflection type liquid crystal display normally comprises a reflective plate, a liquid crystal cell, one or more sheets of optically-compensatory film and a polarizing plate provided therein in this order. The liquid crystal cell comprises a liquid crystal compound, two sheets of substrates for enclosing the liquid crystal compound therein and an electrode layer for applying a voltage to the liquid crystal compound. The liquid crystal cell performs ON/OFF display depending on the difference in alignment of liquid crystal compound. Display modes such as TN (Twisted Nematic), IPS (In-Plane Switching), OCB (Optically Compensatory Bend), VA (Vertically Aligned), and ECB (Electrically Controlled Birefringence), which can be applied to both transmission and reflection type display devices, have been proposed.
As those requiring a high fidelity display among these LCD's there are mainly used 90° twisted nematic liquid crystal displays (hereinafter referred to as “TN mode”) comprising a nematic liquid crystal compound having a positive dielectric anisotropy which are driven by a thin-film transistor. These TN mode liquid crystal displays exhibit excellent display properties as viewed on the front but are disadvantageous from the standpoint of display properties in that they exhibit a lowered contrast as viewed obliquely or gradation inversion during gradation display. It has been keenly desired to provide improvements in these display properties.
On the other hand, wide viewing liquid crystal systems such as IPS mode, OCB mode and VA mode have increased its share with the recent increase of demand for liquid crystal television sets. The display fidelity of the various modes of liquid crystal display has been enhanced from year to year (JP-A-9-211444, JP-A-11-316378, JP-A-2-176625, JP-A-11-95208, JP-A-2003-15134, JP-A-11-95208, JP-A-2002-221622, JP-A-9-80424, JP-A-10-54982, JP-A-11-202323, JP-A-9-292522, JP-A-11-133408, JP-A-11-305217 and JP-A-10-307291). However, these modes of liquid crystal display still leave something to be desired in solution to problem of color difference developed when viewed obliquely.
It has heretofore been known that the retarder plate, particularly ¼ wavelength plate, for polymer aligned film is required to satisfy the relationships 0.6<Δn·d (450)/Δn·d (550)<0.97 and 1.01<Δn·d (650)/Δn·d (550)<1.35 (in which Δn·d (λ) represents the retardation of the polymer aligned film at a wavelength of λ nm) (JP-A-2000-137116).